"I was very fortunate to have really good friends in my life whose parents sort of rallied: 'We're gonna help this kid out, because otherwise there's going to be trouble,.'" he said.

Without their support, he said he "easily" would have lost it.

"I struggled with chronic depression," said Hamm, who can now be seen in Ben Affleck's No. 1 crime drama "The Town." "I was in bad shape. I knew I had to get back in school and back in some kind of structured environment and ... continue."

Also allowing him to bounce back? Therapy, which he said he did "for a brief period."

"It gives you another perspective when you are so lost in your own spiral, your own bulls---," he explained. "It helps."

Antidepressants also aided him.

"Antidepressants help!" he said. "If you can change your brain chemistry enough to think: 'I want to get up in the morning; I don't want to sleep until 4 in the afternoon. I want to get up and go do my s--- and go to work and reset the auto-meter, kick-start the engine!'"